Index termsheusler compounds, magnetic properties, materials science, spin torque transfer, spintronics. Apr, 2015 in mn 2heusler compounds, ferromagnetism might be metastable. The half heusler compounds have thermoelectrical properties. We performed densityfunctional theory calculations for 286 heusler compounds and identified 116 stable. Request pdf tetragonal heusler compounds for spintronics with respect to the requirements of spin torque transfer stt materials, one the most promising. Computational investigation of halfheusler compounds for spintronics applications jianhua ma,1, vinay i. Highly reduced saturation magnetization in epitaxially. However, both tetragonal and cubic phases have their own importance for industrial as well as fundamental research. Tetragonal heusler compounds for spintronics ieee xplore. Noncollinear magnetic structure in tetragonal heusler. The materials with high spinpolarization, high curie temperature, and. Tetragonal mnbased heusler for ultrahigh frequency. Pdf magnetic heusler compounds claudia felser academia.
Tetragonal mnbased heusler for ultrahigh frequency spintronics. This book gives an overview of the physics of heusler compounds ranging from fundamental properties of these alloys to their applications. Noncollinear magnetic structure in tetragonal heusler materials. Cubic heusler, tetragonal, and hexagonal heusler like alloys 3. Band jahnteller type structural instabilities of cubic mn2yz heusler compounds causing tetragonal distortions can be predicted by ab initio band. Cubic heusler, tetragonal, and hexagonal heuslerlike alloys 3. Structure and properties of quaternary and tetragonal heusler. In the present work, the elastic constants and derived properties of tetragonal heusler compounds were calculated using the high accuracy of the fullpotential linearized augmente. Tetragonal heusler compounds for spintronics request pdf. Highpressure investigations on the semiheusler compound. Halfmetallic stability of the heusler alloys tizrirz z. A dinner for workshop participants will be held on thursday evening. Heusler materials, initially discovered by fritz heusler more than a century ago, have grown into a family of more than compounds, synthesized from combinations of more than 40 elements. The key differences between these various heusler compounds are highlighted in table 1.
Mn2heusler compounds crystallize in the inverse structure and are characterized by antiparallel. Sitepreference, electronic, magnetic, and halfmetal. These materials show a wide range of properties, but new properties are constantly being found. In this work, we have conducted detailed growth and characterization along with complementary. Heusler compounds represent a remarkable class of materials with more than 1500 members. However, there are yet to be any reports of 100% spin polarisation experimentally.
Recently, the enhancing of the thermoelectric performance of half heusler compounds are attracted the interest of nanotechnology applications. Tetragonal mnbased heusler compounds, mnga binary 1,2 and mncoga ternary 3, have attracted attentions for nanospintronics applications, such as spintransfertorque magnetic random access memory 4, since those have a small magnetization 5, large magnetic anisotropy 5, lowloss at highfrequency 6, and highelectronic spin. Introduction key to the successful development of spintransfer torque magnetic random access memory sttmram, one of the. Transfer torque applications and its experimental realization j winterlik, s chadov, a gupta, v alijani, t gasi, k filsinger, b balke. In order to further design and develop novel quaternary heusler compounds to meet the demands of spintronics, we have used ab initio electronic structure calculations to identify these interesting compounds for spintronics applications. Quaternary heusler compounds co2x rh x mnz zga, sn, sb. The halfheusler compounds are composed with ternary xyz has a 1. Scope of tetragonal manganese based heusler alloys in context of. Design scheme of new tetragonal heusler compounds for spintransfer torque applications and its experimental realization heusler compounds represent a remarkable class of materials with more than 1500 members. The mismatch can be reduced by introducing larger atoms such as sn. The structural competing and atomic ordering of the full heusler compounds fe 2 nisi and ni 2 fesi under uniform and tetragonal strains have been systematically studied by the firstprinciples calculation. While the tetragonal alloys exhibit features attractive for stt applications high t c, strong pma, high spin polarization, low m s, the cubic systems represent a large class of 100% spin polarized halfmetallic heusler materials that robustly follow the slaterpauling rule similar to the co 2 yz compounds.
G6g8 and gaps of the lnyz heusler family calculated with fully relativistic linear muffin orbitals method vs. Plenary talks will be 40 minutes with 5 minutes for questions, and invited talks will be 30 with 5 minutes for questions and. Heusler in 1903 with the discovery of strong ferromagnetic properties of cu2mnal 1. Heusler in 1903 with the discovery of strong ferromagnetic properties of.
Films of the mnbased tetragonal heuslerlike alloys, such as mn ga, exhibit a large perpendicular magnetic anisotropy pma, small damping constant, small saturation magnetization and large spin polarizations. Request pdf tetragonal heusler compounds for spintronics with respect to the requirements of spin torque transfer stt materials, one the most promising materials families are the tunable. Investigation of the structural competing and atomic ordering. They form the inverse cubic heusler structure with three distinct. The key of spintronic devices using the spintransfer torque phenomenon is the effective reduction of switching current density by lowering the damping constant and the saturation magnetization while retaining strong perpendicular magnetic anisotropy. Butler3,4, y 1department of electrical and computer engineering, university of virginia, charlottesville,va22904, usa. In this paper the many properties of heusler compounds will first be introduced, then their successful application in metallic spintronic devices magnetic tunnel junctions will be described, followed by a discussion on their applications beyond metallic spintronics and their integration with the well established iiiv compound semiconductors and devices. Novel halfmetallic and spingapless heusler compounds. Devices based on spin dynamics in heusler compounds and oxides with low spin. Computational investigation of halfheusler compounds for. The magnetic heuslers with multiple magnetic sublattices are excellent candidates provide a perfect platform to for the design of anisotropic and acentric roomtemperature magnets 5. Towards to this direction, it was reported that the tetragonal phase of the mn 38. On the other hand, several studies have demonstrated that a large number of heusler compounds have the tetragonal structure as the ground state 4,49,5155. Yet quaternary heusler compounds with interesting properties have not been investigated.
The history of one of the most exciting material classes can be traced back to the year 1903 when fritz heusler discovered that an alloy with the composition cu 2 mnal behaves like a ferromagnet, although none of its constituent elements is magnetic by itself. The lowfield mt curves measured within the zerofieldcooled zfc and fieldcooled fc cycles are shown in fig. While they have been known for a long time, 1 it is only in recent years that a wide range. Advancement in heusler compounds and other spintronics. Heusler compounds in devices for spintronic applications 37 6. Journal of optoelectronics and advanced materials vol. Especially heusler compounds as halfmetallic ferromagnetic and topological insulators are important in condensed matter science due to their potential in magnetism and as materials for energy conversion.
Wu1 1beijing national laboratory for condensed matter physics, institute of physics, chinese academy of. In comparison, mn 2 rhsn is a tetragonal heusler compound with moderate mca and a lattice mismatch of only 1. Tetragonal heusler compounds for spintronics semantic. Heusler compounds show high spin polarization in spintronic devices. To reduce the saturation magnetization, particular conditions such as specific substitutions or buffer layers are required. In the present work we suggest a recipe for finding tetragonal heusler compounds with perpendicular magnetic anisotropy pma that also exhibit large tunneling magnetoresistance tmr when used as electrodes in magnetic tunnel junction devices with suitable tunneling barrier materials. The most prominent example is the combination of magnetism and exceptional transport properties in spintronic devices. To conclude, we present a tetragonal stoichiometric i4mmm heusler compound, pt 2 mnga, exhibiting roomtemperature longrange afm spiral order, which possesses a unique combination of properties for the heusler family of materials. Recent advances in novel materials for future spintronics mdpi.
Here we present a theoretical and experimental study on the so far not reported quaternary heusler compounds corhmnz z dga, sn, sb. A critical study of the elastic properties and stability of. Here, we give a comprehensive overview and a prospective on the magnetic properties of heusler materials. Heusler compounds form an intensively studied class of magnetic materials exhibiting novel physical properties due to strong spin polarization of charge carriers at the fermi level, high curie temperatures and martensite structural transitions, with possible application to spintronics and magnetic shape. Sugihara et al 30 report on structure and magnetic properties of mn 3ge compound epitaxial films exhibiting the high perpendicular magnetic anisotropy over 10merg cm. Simple rules for the understanding of heusler compounds. Structural, electronic and magnetic properties of x2yz. Spin gapless semiconductor nonmagnetic semiconductor transitions in fedoped ti2cosi. Tetragonal crystal lattices result from stretching a cubic lattice along one of its lattice vectors, so that the cube becomes a rectangular prism with a square base a by a and height c, which is different from a. Despite the potential importance of tetragonal heusler compounds for spintronic applications, there is still a lack of fundamental understanding.
Apr, 2015 tetragonal heusler compounds with large magneto crystalline anisotropy can be easily designed by positioning the fermi energy at the van hove singularity in one of the spin channels. Heusler compounds with perpendicular magnetic anisotropy. This observation, typical for the tetragonal polycrystalline ferrimagnetic heusler alloys, may result from a random orientation of the anisotropic crystallites 26. Basics and prospective of magnetic heusler compounds.
We demonstrate relaxed epilayers of the tetragonal phase of cumnas grown on gaas. Tetragonal heusler mn 3ge, the one similar to mn 3ga, is another interesting material. Heusler compounds with perpendicular magnetic anisotropy and. Heusler alloys properties, growth, applications claudia. All relaxations started from the c1 b structure with small displacements to avoid vanishing of the net force on each atom due to symmetry. Recently, we find a good method to develop new materials with half metallicity is to combine two heusler alloys which have half metallic properties. The extensive tunability of the heusler compounds through chemical substitutions and structural motifs makes the family especially interesting. With respect to the requirements of spin torque transfer stt materials, one the most promising materials families are the tunable tetragonal heusler compounds based on mn2yz yco,fe,ni,rh, zal, ga, sn. Heteroepitaxial growth of tetragonal mn fe ga 0 x 1. Hegde,2 kamaram munira,3 yunkun xie,1 sahar keshavarz,3,4 david t. The x atoms occupy the wyckoff position 8c 14, 14, 14, the y and the z atoms are located at 4a 0, 0, 0 and 4b 12, 12, 12, respectively. Origin of the tetragonal ground state of heusler compounds.
Antiferromagnetic heusler compounds for spintronics pub. While they have been known for a long time, 1 it is only in recent years that a wide range of their extraordinary functionalities, including halfmetallic hightemperature ferri and ferromagnets, 2 multiferroic shape memory alloys, 35 and topological insulators, 68 have attracted significant. Heusler compounds are a remarkable class of materials with more than members and a wide range of extraordinary multifunctionalities including halfmetallic hightemperature ferri and ferromagnets, multiferroics, shape memory alloys, and tunable topological insulators with a high potential for spintronics, energy technologies, and magnetocaloric applications. With respect to the requirements of spin torque transfer stt materials, one the most promising materials families are the tunable tetragonal heusler compounds based on mn 2 yz y co,fe,ni,rh, z al, ga, sn.
Influence of tetragonal distortion on the topological electronic structure of the half heusler compound laptbi from first principles x. Epitaxial thin films of inverse tetragonal mn2ptsn were synthesized and show lattice. The new materials are quaternary limgpdsbtype compounds contained all atoms in the two parents heusler alloys. Highpressure investigations on the semiheusler compound cumnsb. The tetragonal phase of mn 3x rh x sn has been experimentally determined to be stable up to x 0. Structure and properties of quaternary and tetragonal. Tetragonal heusler compounds for spintransfer torque.
The effect of pressure and alloying on halfmetallicity of. The three main prototypical heusler stoichiometric, chemically ordered structural types, namely half, regular, and inverse, are shown in figure 1. The compounds investigated in these studies contained 3d elements exclusively on the x, x0, and y positions. Normally, heusler compounds have highly ordered cubic crystal structures with different atomic ordering configurations. The findings show that the ferromagnetic phase of type i atomic arrangement is. Influence of tetragonal distortion on the topological. Since tetragonal heusler compounds have many potential applications in spintronics and. Design scheme of new tetragonal heusler compounds for spin. However, several recent studies have found many heusler materials have tetragonal structure as the ground state, e. Compensated ferrimagnetic tetragonal heusler thin films for. Heusler alloy thin films with a distorted tetragonal structure have potential spintronics applications given their bulk perpendicular magnetic anisotropy. Thin films of these materials have been shown to exhibit large pma for films grown.
Complete spin gapless semiconductivity in equiatomic. Tetragonal mnbased heusler compounds, mnga binary 1,2 and mncoga ternary 3, have attracted attentions for nano spintronics applications, such as spintransfertorque magnetic random access memory 4, since those have a small magnetization 5, large magnetic anisotropy 5, lowloss at highfrequency 6, and highelectronic spin. Lastly, the uniform and tetragonal strains have been accessed and their effects on the electronic and magnetic properties have been studied. While they have been known for a long time, 1 it is only in recent years that a wide range of their extraordinary functionalities, including half. Heusler compounds have been predicted to be halfmetallic possessing integer magnetic moments due to complete spin polarisation at the fermi level, a property highly desirable in spintronics. In this article we highlight recent major developments in the field of. This is essentially due to their exceptional magnetic properties, which qualify them as promising functional materials in various datastorage devices, such as giantmagnetoresistance spin valves. Nayak, journalieee transactions on magnetics, year20, volume49, pages682685.
The heusler compounds also exhibit good thermoelectric properties 1719 and. This systematic study can provide a comprehensive reference for the further development of ti and zr based quarternay heusler compounds and even inspire other relative studies for the exploration of new. Structure and properties of quaternary and tetragonal heusler compounds for spintronics and spin transfer torque applications. Jan 18, 2016 heusler alloy thin films with a distorted tetragonal structure have potential spintronics applications given their bulk perpendicular magnetic anisotropy. Compensated ferrimagnetic tetragonal heusler thin films. Compared to the convenient co2mnz heusler compounds 17,18, one co atom was substituted by rh. Investigation of the structural competing and atomic. Structural, elastic, electronic, magnetic and thermoelectric. Structure and properties of quaternary and tetragonal heusler compounds for. Both fe 2 nisi and ni 2 fesi have the xa structure in cubic phase and they show metallic band structures and large magnetic moments greater than 3. For spintronic application, the magnetic heusler compounds and halfmetals, in particular, are of utmost interest. Heusler compounds are a large family of binary, ternary, and quaternary compounds that exhibit a wide range of properties of both fundamental and potential technological interest. In recent years, hh compounds with hm properties have been widely reported 2123.
The lattice parameters of the tetragonal cell are a 3. Heusler alloys for spintronic devices will begin the morning of thursday, july 30th and at 3. In analogy to the iamnv compounds, all nearest neighbours in the tetragonal cumnas. Similar to halfheusler materials, this structure consists of four interpenetrating fcc sublattices, two of. In crystallography, the tetragonal crystal system is one of the 7 crystal systems. Robust spingapless behavior in the newly discovered half. This class of heusler compounds offer a degree of flexibility which is lacking in binary and pseudobinary ferromagnetic.
The free carrier spin polarization at the fermi level is an important property and is given by. In the recent decade, the family of heusler compounds has attracted tremendous scientific and technological interest in the field of spintronics. Tetragonally distorted heusler compounds have attracted interest in the field of spintronics, in particular, for spintorque applications, owing to their. Also, there could be various defects present in both structures, including disorder, antisite, swap and vacancy. Compensated ferrimagnetic tetragonal heusler thin films for antiferromagnetic spintronics roshnee sahoo 1, lukas wollmann 1, susanne selle 2, thomas hoche 2, benedikt ernst 1, adel kalache 1, chandra shekhar 1, nitesh kumar 1, stanislav chadov 1, claudia felser, stuart s. The halfheusler compounds have eight valance electrons, including a large number of semiconductors with energy gaps vary in a wide range 9. In general, the heusler compounds have face centered cubic crystal structures, which are either the fullheusler or the halfheusler structures with lattice parameters ranging from 5. Some examples of tetragonal heusler compounds are mn3. Dec 11, 2012 it is important to emphasize that while tetragonal distortion is a necessary condition, it does not guarantee perpendicular magnetization in thin films as reported recently for the related tetragonal heusler compounds rh 2 yz. The study of the structural, mechanical, and magnetoelctronic properties of tizrirz z al, ga, in quaternary heusler alloys was performed using fullpotential linearized augmented planewave fplapw method, based on the density functional theory dft with generalized gradient approximation gga. These ternary intermetallic compounds were introduced by f. Casper, others, design scheme of new tetragonal heusler. Halfmetallic heusler compounds have been the subject of numerous studies for their versatile properties and particularly for their potential applications in spintronics. These properties are attractive for the application to the next generation high density spintransfertorque stt magnetic random access memory sttmram.